but Japan is actually relaxing immigration rules due to the need for younger workers. I bet they can pay them pretty well for less than the R&D, maintenance, and loss of productivity of the robots costs

Long term.. not sure that I agree. The cost of creating robots is going to go down. It's already relatively cheap to produce most of the robot, it's more down to the software development itself at this point. Also, even if a robot costs 2x what you would pay a person in a year at half the speed of a person, that robot can work effectively 4x as many hours a week as a person can.

My bigger concern to me is a conglomerate like ConAgra for robot farming comes in and only leases access to these machines instead of being able to buy/maintain/adapt them on the farms themselves. Leading to one more point of pressure against smaller farms in favor of larger conglomerates squeezing every bit of value from the middle out.